Contactor



July 19, 1949. I 0, us 2,476,794

.CONTACTOR Filed 001:. 8, 1945 2 Sheets-Sheet 1 QQIF WlTNESSESZ INVENTORZ6 Basaum O. flUJ/lh.

- BY k. 024/6.

ATTORNEY y 1949. B. o. AUSTIN 2,476,794

CONTACTOR Filed Oct. 8, 1945 2 Sheets-Sheet 2 WITNESSES: INVENTOR 5625aum 0, //z/: 160, BY

M *M Ma". W

ATTORNEY Patented July 19, 1949 CONTACTOR Bascum 0. Austin, Lima, Ohio,assignor to Weatinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Application October 8, 1945, Serial No.621,080

My invention relates to electric contact devices such as electromagneticcontactors or relays and has for its main objective to improve theswitching performance of this type of device by reducing the possibilityof contact freezing or the disturbing effects caused by such freezing.

To this end, and in accordance with my invention, I provide the movableassembly of the contact device with an inertia weight which is movablerelative to the movable contacts and coopcrates with thecontact-pressure spring of the assembly to impose during the switchinperformance an inertia effect on the contacts in order to produce atransient force between the movable contacts and the appertainingstationary contacts. This temporary force is effective when closing thecontacts to diminish bouncing and the attendant arcing or sparking atthe contacts, thus reducing the cause of freezing; or it acts whenopening the contacts to force the contacts rapidly apart in order tosecure a separation of the contacts even if they are slightly frozen.According to a preferred way of embodying the invention, and as will beexemplified hereinafter, the device may be so designed that a singleinertia weight is capable of performing both above-mentioned functions.

The invention has proved especially favorable for electromagnetic relaysand contactors of small dimensions and relatively high switchingcapacity as used, for instance, in aircraft and therefore is representedin the drawing by the example of a relay for such purposes.

In the drawing, Figure 1 represents an axial section through a contactoraccording to the invention; Fig. 2 is a lateral view; Fig. 3 is a sideview of the same contactor at a right angle to the view of Fig. 2; andFig. 4 is a diagram of the appertaining circuit connections.

According to the drawing, the contactor has a substantially U-shapedmagnetic frame structure l with outwardly extending flanges 2 and 3. Amagnetic core 4 is firmly attached to the bottom of the U-shaped framestructure I by means of a screw 5. The core 4 carries a pickup coil 6and a high-resistance holding coil 1. A face plate 8 of magnetizablematerial is mount ed on flanges 2 and 3 and forms together with core 4an annular interstice. The pole faces of core 4 and face plate 8 lie ina common geometrical plane.

A base 8 is mounted on plate 8, and parts I, 8

and 8 are firmly secured together by means of 8 Claims. (Cl. 20087) 2screws III which engage corresponding threaded bores of flanges 2 and 3.

A guide pin H extends coaxially to core 3 and is firmly secured thereto.A sleeve member I2 is slidably seated on the guide pin II and carries anarmature IS. The sleeve and armature assembly is biased by a kickoutspring I4 in the direction away from the core.

A guide post l5, attached to the base 9, engages the recessed end of anarm l6 which is brazed to a shoulder of the sleeve member 12 and carriesan insulating button ll. Two contact springs l8 and I! are attached tothe base 9. In the illustrated position of arm It, the contact spring 18rests resiliently against the contact spring 19 so that a circuitconnection is established between springs l8 and I9 or the terminals andwires attached thereto. When arm I 6 moves upwardly with reference tothe showing in Fig. 1, button ll engages the contact spring l8 and movesit out of contact with spring l9. Contact springs l8 and I9 form anauxiliary contact device for controlling the excitation of the holdingcoil '1 as will be explained below in conjunction with Fig. 4.

The main contact device of the relay comprises a movable bar-shapedcontact member 20 which carries two contacts 2! and 22 for engagementwith two respective stationary contacts 23 and 24 (Fig. 3). Contacts 23and 24 are fastened to base 9 by means of screws 25 and are associatedwith terminals 26 and 21, respectively, for connection to the circuit tobe controlled. The contact member 20 is slidable on sleeve l2. Aninertia weight 28 is also slidably seated on the sleeve [2. A helicalcontact-pressure spring 29 tends to hold the contact member 20 againstthe adjacent stop or abutment formed by the arm l6 while holding theweight 28 against a retainer 30 fastened to the sleeve member l2.

When the core 4 is magnetized by electric energization of coil 6, thearmature i3 is attracted in opposition to the biasing force of thespring l4. When the armature reaches the closed position, it sealsagainst pole faces of core 4 and plate 8 so that thereafter a reducedmagnetic force suffices to maintain the device in closed condition. Inaccordance therewith, the relay control circuit is so designed that thehigh-resistance holding coil 1 lies in series with the low-resistancepick-up coil 6, but is shorted by the contact springs l8 and I9 when therelay is in dropped-off condition. Hence, only coil 6 is at firsteffective to actuate the relay. When coil 8 is energized and after thearmature i3 for energizing the relay coils 6 and 1.

has moved the contacts 2| and 22 into engagement with the stationarycontacts 23 and 24, the member is stopped while the armature l3 and thesleeve l2 with arm ii are permitted to travel a further extent underincreasing compression of the contact pressure spring 29. During theperiod of this overtravel motion and shortly before the armature l3seals against the magnet, the engagement of contacts I8 and I9 isinterrupted; Thls'interruption eliminates the short circuit of holdingcoil 1 so that the latter becomes energized in series with the pick-upcoil 6. Hence, a reduced current is thereafter effective to hold therelay closed. This performance will be more fully understood from thecircuit diagram of Fig. 4 in which the main contact device of the relayis schematically represented at M and the auxiliary contact device at A.The load circuit to be controlled by contact device M is denoted by L,while C indicates the control circuit When a switch or contact S in thecontrol circuit is closed, the pick-up coil 6 is energized and causesthe relay to first close contact device M and then open the contactdevice A. Thereafter, both coils 6 and I are excited in seriesconnection until contact S is opened.

During the above-described closing motion of the movable armature andcontact assembly, starting from the position shown in Figs. 1 and 3, theinertia weight 28 is caused by the retainer 30 to follow the movementof'the armature l3 and sleeve l2. After the contacts 2| and 22 of thecontact member 20 abut against the stationary contacts 23 and 24, afurther movement of member 20 is prevented. Slightly later, the armaturel3 abuts against the pole faces of the field structure and is alsostopped. The weight 28, however, due to its inertia will now continue tomove a further extent toward the stopped contact member 4 20, thusseparating itself from the retainer 30. As a result, the spring 29 isadditionally compressed and exerts temporarily an increased force on themember 20. This force prevents the contacts from bouncing and chatteringand thus stabilizes the switching-in performance of the relay. Whenthereafter the inertia effect of the Weight 28 ceases, the danger periodof resonant vibrations of the movable contacts has passed so that thepersisting amount of sprin force suffices to hold the contacts safely inclosed condition under the contact pressure required for a permanenttransmission of current.

During the opening motion of the armature assembly, the armature l3 andsleeve I2, together with the inertia weight 28, start moving away fromthe field structure of the relay before the part l6 comes intoengagement with the contact member 20. At the moment of engagement, theinertia of the moving weight 28 causes a hammer efiect to take placebetween the sleeve l2 or the part l6 attached thereto and the contactmember 20 so that suddenly a relatively great force is applied. Thisforce suifices to secure a separation of the contacts even if they areslightly frozen.

It thus will be understood that the embodiment of my inventionrepresented by the drawing utilizes the inertia effect of the weight 28in two ways, thus reducing the tendency of arcing from the principle andgist of the invention and within the essential features of the inventionas set forth in the claims annexed hereto.

I claim as my invention:

1. A contact device, comprising a stationary contact, movable contactmeans, electromagnetic means having an armature for controlling saidcontact means to move between opening and closing positions relative tosaid stationary contact, an inertia weight movable relative to saidarmature and relative to said contact means and associated with saidarmature to move in the direction of motion of said contact means duringchanges of position of said contact means, stop means effective betweensaid weight and said contact means for limiting the motion of saidweight in the direction away from said contact means, and a springdisposed between said weight and said contact means, said weight havinga mass rated relative to the biasing force of said spring so as to moveprior to the motion of said contact means when said contact means arecontrolled to move into said opening position, whereby said weight iscaused to thereafter exert a hammer effect through said stop means onsaid movable contact means if the latter tend to freeze to saidstationary contact.

2. An electromagnetic contact device, comprising a stationary contact,movable contact means engageable with said stationary contact,electromagnetic means having an armature structure movable between twopositions for controlling said movable contact, an inertia weightdisposed on said structure and being movable relative to said structureand relative to said contact means, said contact means being disposedbetween said armature and said .weight, a contact-pressure springarranged to bias said weight and said contact means away from each othertoward given 0 respective positions relative to said armature structureso that, when said structure changes its position, said weight is causedby its inertia to move relative to said structure toward said contactmeans in opposition to said spring for reducing bouncing between saidcontact and contact means.

3. A contact device, comprising a stationary contact, movable contactmeans engageable with said contact, electromagnetic means having anarmature structure movable between two positions and biased toward oneof them, said movable contact being movably mounted on said structure soas to permit an overtravel motion of said structure when the lattermoves toward one of said positions and after said contact means haveestablished engagement with said contact, a contact-pressure springengaging said contact means and disposed to bias said contact meanstoward a given position relative to said structure so that said springis stressed due to said overtravel motion, and an inertia weight mountedon said structure so as to be movable relative thereto and relative tosaid contact means, said weight being engaged by said spring and havingan inertia 68 mass of suflicient magnitude relative to the force of saidspring to move, due to inertia, relative to said contact means aftersaid contact means touch said contact and before said contact meansseparate from said contact.

4. A contact device comprising a stationary structure having anelectromagnet and a stationary contact, an armature structure movablerelative to said magnet between magnetically open and closed positions,means for biasing said arma- 76 ture structure toward the open position,contact means disposed on said armature structure for engaging saidstationary contact when said armature structure is in one of saidpositions and being movable relative to said armature structure in thedirection of motion of the latter, said armature structure forming anabutment for limiting the relative motion of said means toward one side,an inertia weight also forming part of said assembly and being movablerelative to said armature structure and said contact means in saiddirection, said armature structure having a rigid abutment for limitingthe relative motion of said weight toward the other side, acontact-pressure spring disposed so as to bias said weight and saidcontact means apart from each other toward said respective abutments,said weight having sufficiently large mass to perform due to its inertiaan c-vertravel motion in opposition to said spring toward said contactmeans after the latter is moved into engagement with said stationarycontact during a change in position of said armature structure therebypreventing bouncing between said contact means and said stationarycontact.

5. A contact device, comprising a magnet core, a guiding pin projectingfrom the core, a. sleeve slidably mounted on said pin so as to bemovable toward and away from said core, an armature attached to saidsleeve at the side of said core, a spring for biasing said sleeve andarmature away from said core, a contact member and an inertia weightslidably seated on said sleeve, said contact member being disposedbetween said armature and said weight, a contact-pressure springarranged so as to bias said member and said weight away from each othertoward given positions relative to said sleeve, and stationary contactmeans to be engaged by said member in one position of said armature,said inertia weight having a mass rated relative to the biasing force ofsaid contact-pressure spring so as to lag temporarily behind the motionof said sleeve in opposition to said latter spring in order to therebyrender a transient force effective between said member and saidstationary contact means.

6. A contact device, comprising a stationary structure having anelectromagnet and stationary contact means, an assembly comprising anarmature and a sleeve portion, means forming part of said structure forguiding said assembly for motion toward and away from said magnet, aspring for biasing said assembly away from said magnet, said sleeveportion forming two axially spaced abutments, a contact member slidablyseated on said sleeve portion for engaging said stationary contact meanswhen said assembly moves toward said magnet, an inertia weight slidablyseated on said sleeve portion at the side of said member opposite saidarmature, a contact-pressure spring disposed between said member and CPLsaid weight so as to bias them toward said abutments respectively, saidinertia weight having a mass rated relative to the biasing force of saidcontact-pressure spring so as to lag temporarily behind the motion ofsaid sleeve portion in order to render a transient force effectivebetween said member and said stationary contact means.

7. A contact device, comprising a stationary structure having aneieotrom'agnet and stationary contact means, an assembly comprising anarmature and a sleeve portion, means for guiding said assembly formotion toward and away from said magnet, a contact member slidablyseated on said sleeve portion for engaging said stationary contact meanswhen said assembly moves toward said magnet, an inertia weight slidablyseated on said sleeve portion at the side of said member opposite saidarmature, and a spring disposed between said contact member and saidweight to bias them to limiting positions on said sleeve portion, saidinertia weight moving from its limiting position toward said armature inopposition to the action of said spring, after said contact member hasengaged said contact means, to temporarily increase the engagementpressure therebetween.

8. A contact device, comprising a stationary structure having anelectromagnet and stationary contact means, an assembly comprising anarmature and a sleeve portion, means for guiding said assembly formotion toward and away from said magnet, a contact member slidablyseated on said sleeve portion for engaging said stationary contact meanswhen said assembly moves toward said magnet, an inertia weight slidablyseated on said sleeve portion at the side of said member opposite saidarmature, and a spring disposed between said contact member and saidweight to bias them to limiting positions on said sleeve portion, saidinertia weight moving from its limiting position toward said armature inopposition to the action of said spring, after said contact member hasengaged said contact means, to temporarily increase the engagementpressure therebetween, and said inertia weight moving along with saidassembly prior to the opening motion of said contact member tothereafter exert a hammer effect on said contact member to assist theopening movement thereof.

BASCUM O. AUSTIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,817,155 Leece Aug. 4, 19312,238,154 Borgkvist Apr. 15, 1941

